The absorbents of this invention may be used for a wide variety of absorbent.backslash.adsorbent (collectively referred to herein as "absorbent") applications. The absorbents are particularly well suited for use as animal litters and abatement of the odors commonly associated with use of such absorbents in animal litter boxes. A search of the prior art relating to animal litters located the following patents:
______________________________________ U.S. PAT. NO. DATE OF PATENT PATENTEE ______________________________________ 2,649,759 8/1953 Gibbs 3,286,691 11/1966 McFadden 3,765,371 10/1973 Fisher 4,009,684 3/1977 Kliment et al. 4,275,684 6/1981 Kramer et al. 4,315,761 2/1982 Larrson et al. 4,343,751 8/1982 Kumar 4,395,357 7/1983 Kramer et al. 4,409,925 10/1983 Brundett et al. 4,459,368 7/1984 Jaffee et al. 4,494,481 1/1985 Rodriguez et al. 4,494,482 1/1985 Arnold 4,506,628 3/1985 Stockel 4,532,890 8/1985 Ohki et al. 4,570,573 2/1986 Lohman 4,591,581 5/1986 Crampton et al. 4,638,763 1/1987 Greenberg 4,641,605 2/1987 Gordon 4,657,881 4/1987 Crampton et al. 4,671,208 6/1987 Smith 4,685,420 8/1987 Stuart 4,686,937 8/1987 Rosenfeld 4,844,010 7/1989 Ducharme et al. 5,000,115 3/1991 Hughes 5,062,383 11/1991 Nelson 5,129,365 7/1992 Hughes 5,317,990 6/1994 Hughes 5,452,684 9/1995 Elazier-Davis et al. Re. 33,983 7/1992 Hughes 87001 8/1913 EPO 0087001 8/1983 EPO 0242478 10/1987 EPO 0378421 7/1990 EPO 0424001 4/1991 EPO 3620447A1 12/1987 Fed. Rep. Germany 58-009626 1/1983 Japan 0094043 5/1985 Japan 63-219323A 3/1987 Japan 3044823 2/1988 Japan 3185323 7/1988 Japan 1191626 8/1989 Japan 58009626 7/1981 Japan 00094043 5/1985 Japan 1119127 6/1986 Japan 239932 10/1987 Japan 2239932 10/1987 Japan 1191626 1/1988 Japan 63-44822 2/1988 Japan 44823 2/1988 Japan 3044822 2/1988 Japan 3044823 2/1988 Japan 185323 7/1988 Japan 3185323 7/1988 Japan 3219323 9/1988 Japan ______________________________________
The following patents relate to bentonite-containing animal litters: U.S. Pat. Nos.: 4,591,581; 4,657,881; 5,000,115; 5,129,365; 5,317,990; 5,452,684; and Re. 33,983 (hereinafter the "Hughes Patents"). Further, the foreign patents listed above (and other prior) may be located in the prosecution histories of the Hughes Patents.
Several patents disclose general use of activated carbon to absorb odors when used with absorbents for liquids in numerous absorbent applications, and include:
______________________________________ U.S. PAT. NO. PATENTEE ______________________________________ 4,638,763 Greenberg 4,793,837 Pontius 5,019,254 Abrevaya 5,224,975 Purnell, et al. 5,306,487 Karapasha et al. 5,407,442 Karapasha 5,468,447 Bermas ______________________________________
U.S. Pat. No. 4,638,763 discloses the use of anhydrous sodium sulfate in an animal litter to bind animal urine. In one embodiment the litter can also optionally contain approximately 2% by weight, based upon the weight of anhydrous sodium sulfate of activated carbon granules. The patentee does not designate any particular type of litter, generally including, clays, silica, limestone, vermiculite, sawdust and ground alfalfa among acceptable absorbent materials (column 1, lines 56 to 66). The amount of anhydrous sodium sulfate is stated to be from 0.5 to 4 parts per 100 parts (apparently by weight) of animal litter base with any optional activated carbon component being approximately 2% by weight of the anhydrous sodium sulfate. The patentee provides two examples which disclose a first composition formed from an unspecified clay and a second composition formed from sawdust. The patent states at column 3, lines 6 to 9 that "The purpose of the activated carbon granules is to absorb the odor producing substances which form part of, or are generated by, the feces and urine materials found in the litter." Based upon examples 1 and 2, the amount of activated carbon granules used by the patentee indicate the use is primarily as a chemical ingredient, since examples 1 and 2, respectively, employ 0.06 wt. % and 0.07 wt. % activated carbon granules, based on the total weight of the litter. The use of activated carbon granules in such small amounts as employed by the patentee, are clearly for some purpose other than odor absorption.
U.S. Pat. No. 5,407,442 discloses carbon-containing odor control compositions for a wide variety of uses to control malodors associated with body fluids. The particles are formed by combining white odor-controlling agents with activated carbon by means of binders. The patent also discusses the use of activated carbon and the general control of odor in sanitary products such as diapers, bandages and catamenials.
The prior art contains numerous patents on animal litters of various types. The use of animal litters having both clumping and nonclumping qualities are well established consumer products. Although consumers have used a wide variety of clay and non-clay materials with various additives to provide animal litters, the primary growth market for animal litters is in the area known as "clumping litters". The advantages stated to arise from clumping litters are the savings in the use of litter, the removal of used litter from a litter box and the associated removal of odor causing fecal matter and urine with the removed clumps of used litter. Although waste products are removed, the odors associated with the repeated use of the litter nonetheless is significant consumer complaint. This problem has been the subject of a large number of patents relating to various chemical additives to absorb and.backslash.or mask odors. These patents alternatively seek to react with ammonia and/or urea or serve as a masking agent for odors; e.g., fragrances.
The most widely used and best known material used for clumping litters is disclosed and claimed in the Hughes Patents, including U.S. Pat. No. Re. 33,983, i.e., water-swellable bentonites. Bentonite clays are routinely mined, dried, ground into a useable particle size distribution and sold for use in animal litter boxes, in particular, for use in feline litter boxes (a.k.a. cat litter boxes). Although the use of water-swellable bentonite materials as animal litter is well established and has grown in the last several years to represent a significant percentage of all animal litter sold, the use of such water-swellable bentonite materials has undergone little change or improvement over the last several years as to its odor control characteristics. Manufacturers have provided variations in fragrance, appearance, particle size and provided various other additives in an attempt to provide product differentiation to consumers in their bentonite-based litter products, but no significant changes in odor control during the use of animal litter in the litter box have been introduced.
The manufacturing process for bentonite-based litters generally involves a drying, grinding and sizing process for mined, field dried bentonite pursuant to which a ground bentonite product is put into containers and then sold to consumers. Several patents have specifically claimed the use of bentonite-containing clays for use as animal litters. The several patents issued to John Hughes (U.S. Pat. Nos.: 5,000,115, 5,129,365, 5,317,990 5,452,684; and Re. 33,983 of U.S. Pat. No. 5,000,115; the "Hughes Patents"; incorporated herein by reference thereto) disclose the use of a water-swellable bentonite clay for use as an animal dross absorbent. For example, Re. 33,983 discloses and claims the use of a water-swellable bentonite clay having a particle size from about 50 microns to about 3350 microns and having a sufficient amount of fine particles so that upon wetting, a substantial quantity of the clay will agglomerate.
Several commercially available consumer animal litters have been introduced as dedusted animal litters using fluoropolymers to reduce the dust (small particles which can become airborne during use) in bentonite-based litters. Such dedusting processes using fluoropolymers are generally known in the art as evidenced by the disclosure in U.S. Pat. Nos. 3,838,064; 3,993,584; 3,838,092; and 3,974,089; said patents incorporated herein by reference.
U.S. Pat. No. 5,109,805 discloses the use of a particular class of bactericides for use in animal litters to control bacterial growth during use of the animal litter.
The instant invention relates to absorbents containing activated carbon in an effective odor absorbing amount to provide odor absorbency when used as absorbents and in one embodiment to a litter formed from an inorganic absorbent base material, fluoropolymer and activated carbon. Other embodiments of the invention are discussed below.